Grinding mill



July 7, 1936. VAN LAW 2,046,711

GRINDING MILL Filed Dec. 27, 1952 2 Sheets-Sheet l 9 .92 .39 4 -4 ,2: 4 2 24- I 6 5 i 7 as 7' 2 .54 44 45 3 '2- 47V a 5' g i 1 ll 2 46-; 1" n 1 INVENTOR.

ATTORNEYS D. VAN LAW July 7, 1936.

GRINDING MILL Filed Dec. 27,: 1932 2 Sheets-Sheet 2 INVENTOR. X?

ATTORNEYS PatentedjJuly 7, 1936 UNITED STATES GRINDING MILL Durbin Van Law, Denver, 0010., assignor to Powder-co, Inc., Denver, Colo.

Application December 27, 1932, Serial No. 649.009

4 Claims.. (Cl. 83-46) v This invention relates to grinding mills and I more particularly to certain new and useful improvements in mills of the type shown and a pulverized'fuel to the combustion chamber of a furnace and an object of the present invention is to provide a mill in which the fuel is preheated by a connection with the burner of the furnace. This burner is the subject of a separate application for patent.

The mill comprises a grinding element and a fan-element in cooperative relation, and the improvements comprised in the present application consist mostly in'details of construction and an arrangement of parts which render the mill more efficient andpractical in operation and construction.

In the accompanying drawings, in the severalviews of which like parts are similarly designated,

Figure 1 is a sectional elevation of the improved mill,

- Figure 2 is a composite view, looking in the direction of the arrows on the line 2-2 of Figi Figure. 3 is a partially sectional the mill,

Figure 4 is a section taken on the line 4-4 of Figure 1, I p

Figure 5 is a fragmentary section in the plane indicated by the line 5-5 inFigure 3, and

Figure 6 is a fragmentary section on the line 66 of Figure 4.

' The mill comprises an'annular base-plate 5 supported on legs 6 provided with levelingscrews I. Suspended from the base plate is anelectric motor 8 having in connection with its rotor, a shaft 9 extending upwardly in the vertical axis of the annulus. On this shaft are mounted the grinding element A and above the same the fan element B.

The last-mentioned element consists of a drum ll having circumferentially, a plurality of curved vanes II. The drum is closed at its top and' open at its bottom for the admission of fuel carrying air-currents. I

A hub l3 below the top-plate ll .of the fan, is mounted on the shaft l5.

, The grinding element has a two-part top-view of hub, the

inner member l6 of which is connected to the shaft by a key I! and a set screw II. The outer and secured by a key member I9 is connected with the inner member by a shear-pin driven into-'alined openings of the members.

Above the hub is a collar 2| fastened to the shaft by a set screw 23, whichprevents upward 5' movement of the grinding element, when the members of the hub are disconnected by breakage of the pin. The object of the shearing pin is to prevent breakage of the parts of the grinding element, in case its rotary movement is op- 10 posed by obstructions or in the event of an overload. I

Integrally connected with the outer member of the hub by means of a solid 'web 24 and spokes 25, is the annular rim 26 upon which are 5 mounted equidistantly, the peripheral vanes or vpaddles 21. These paddles project over and beyond the top surface and the peripheral surface of the rim and are secured by countersunk machine screws 28. The same screws secure a go shroud ring 29, which rests upon the paddles and covers the spaces between the same.

A distinctive feature of the paddles is that their sides forward with relation to the direction of rotation of the grinding element are beveled A- dome-shaped circular housing 32 is fastened 35 upon the base-plate 5 by bolts 33. It encloses the fan element and the grinding element, and it is divided by means of a' plate 34 to provide a grinding chamber 35. Between the dividing plate and the top of the housing is a scroll-[ shaped wall 36 formed integral with the housing and surrounding the fan element in spaced relation thereto. The scroll extends to, a periphe'ral opening of the housing where it connects with a conduit 31 leading to the burner of the furnace. Around the grinding element in spaced relationto .the outer endsof the paddles, is a cast iron impact or curb ring 38, and between this ring and the surface of the housin are wedges 38 of rubber or other resilient material which deaden the sound of. the impact.

Upon these wedges and upon the curb-ring rests the dividing plate 34, and upon the dividing plate engages the scroll-wall 36 of the famelement. Paper gaskets l0 and 4| between the ring 38 and the plate 34 and between the plate and the lower edge of the scroll-wall'36 provide dustproof and sound deadening packings.

The dividing plate abuts against lugs 42 projecting inwardly from the housing and it is thus held firmly in position without the use of bolts or other fastening devices.

Between the base plate and the impact ring 38 is a bottom plate 43 for the grinding chamber, and again, dustproof and sound-deadening connections are provided by paper gaskets 44 and 45 interposed between the bottom plate 43 and the lower edge of the impact ring and between the bottom plate and the base plate 5.

The bottom plate and the'gasket 45 have a series of openings 46 concentric with the shaft, and rotatable on the shaft, is a valve or shutter 41 provided with ports 48 which register with the openings.

A handle 49 projects from the shutter beneath the base plate and a bolt 50 on the depending rib 52 allows adjustment of the movement of the handle by engagement with the mounting plate ii of the motor.

The openings 46 and the valve are the media for admitting air to the fan-inlet in regulatable quantities.

At the periphery of the rim of the grinding element, between the paddles, are bosses 53 functioning as projectors which in the operation, return coarser particles of the material into the path of the paddles until they are reduced to the desired size.

It is to be noted that the grinding element is separated from the bottom plate by a space 54, which, together with the velocity of the air currents admitted through the openings of the a bottom plate, determines the fineness to which the fuel is reduced.

In the operation of the mill, the material is fed onto the dividing plate through an opening 56 in the dome of the housing and thence passes through openings 66 in the dividing plate onto the web 24 of the grinding element, from where it is thrown into the spaces between the paddles and against the impact ring, it being understood that the two elements mounted on the rotor shaft are rotated at a comparatively high velocity. r

The grinding-vanes reduce-the material to. a

fineness which permitsof their passage through the space 64 between the rim of the grinding element and the bottom plate 43,01 the grinding chamber, to be carried upwardly by the air currents drawn through the air-openings 46 by the movement of the fan. The fuel-laden currents are thrown outwardly through the spaces between vanes of the fan into the scroll wall 36 to be drawn through the conduit 31 to the burner of the furnace.

Heated air from the furnace may enter the housing through an opening 51 and not only aids in the movement of the fuel, but also preheats the same before it enters the burner of the furnace.

The form of the blades 21 of the grinding element is of importance in the operation, since they provide for the co'mminution of the material, both by impact and by attrition.

The upper portions of the blades provide impactors, which, in cooperation with the 38, reduce the material by. impact.-

The bulk of the material accumulates in the spaces provided by the lower, beveled portions 'wardly from its peripheral edge, a passageway 21c.of the paddles, and is there reduced by attrition; The shroud ring 29, covering the spaces between the paddles, prevents back firing of the material, there being a tendency of coal dust to rise and back up through the air ports or 5 through the feed-pipe. This shroud ring is essential to the satisfactory operation of the mill. The projectors 53 throw coarse particles in the material back into the path of the bulk of the material until they are reduced to the desired 10 size.

The shutter 41 regulating the size of the openings 46, is of importance since the inflow of air determines the grinding period and thereby the fineness to which the material is reduced. The 15 construction of the mill combines practicability with'simplicity and low cost of production.

The one-piece housing encloses all the working elements, it includes the fan scroll as an integral part, and it provides for securing the 20 division plate, and the impact-ring.

The operation is rendered practically noiseless by the provision of the paper gaskets and the rubber wedges. All of the parts are easily removed and replaced in case of wear and g5 breakage, and by making the parts of light metal, such as aluminum, the entire device may be made portable. v

The sheer pin prevents breakage in the event of an overload or the introduction of foreign ob- 3o jects with the feed, and when the pin is broken, the safety collar 2| prevents the grinding wheel from moving upwardly on the shaft. v

What I claim and desire to secure by Letters Patent is: 85

1. In agrinding mill, a housing having a circular impact surface, a base, a grinding chamber, a rotor in the circle of said surface spaced from said base and having vanes projecting outor conduit formed through said rotor, a shroudring on the rotor closing the spaces between the vanes, the periphery of the shroud-ring being substantially coincident with the outer edge of the vanes, the space between the rotor and base communicating with said passageway and together forming a continuous passageway from the grinding chamber through the rotor, and suction means for the upward movement of ground matter through said continuous passage- 50 way.

2. In a grinding mill, a grinding chamber with a flat chamber wall, a housing having a circular impact surface and having an outlet for the prod uct of the grinding action, a rotary grinding 4;]; element within the circle of said surface, spaced from a wall of the housing to admit the product I of the grinding action, said rota y grinding element having an imperforate annular rtion, annular guiding and deflecting means spacedabove said imperforate portion and rotatable therewith, the grinding chamber located on one side of'said imperforate portion, a passageway located in the grinding element on the other side of the imperforate portion, the annular 5 imperforate portion being located with an edge adjacent a fiat chamber wall to define an entrance for air and ground material from the grinding chamber to the passageway, .feed and air inlet means for the grinding chamber and 70 suction means connected with the passageway for drawing air-borne ground material from the grinding chamber through the entrance and passageway.

3. a grinding mill comprising a fiat walled base, a housing internally shouldered, apartition fitted against the shoulder of the housing and separating the housing into a grinding chamber and a suction chamber, a rotary grinding element within the grinding chamber, said rotary grinding element having an" 'imperi'orate annular portion, the grinding chamber located on one side of said imperforate portion, annular guiding and deflecting means spaced above said imperiorate portion and rotatable therewith, the grinding element being spaced from said base and provided with a passageway therethrough on the other side of the imperiorate portion, the annular imperiorate portion being located with an edge adjacent a flat chamber wall to define an entrance for air and ground material from the grinding chamber to the passageway, feed and air inlet means for the grinding chamber, a suction element in the suction chamber connected with the passageway for drawing air-borne ground material from the grinding chamber through the entrance and eway.

4. A grinding mill comprising a housing, a base,

a grinding chamber in the housing, a rotary grinding element in the grinding chamber spaced from the base and a wall of the housing to admit the ground product, said rotary grinding element having. an imperiorate annular portion, a grinding chamber located on one side of said imperi'orate portion, annular guiding and deflecting means spaced above said imperforate portion and rotatable'therewith, a passage through said grinding element, the space between the grinding element and the wall and the base communicating with said passage, a suction chamber, a suction element in the suction chamber whereby the ground product i conducted from the grinding chamber directly to the suction element. and means to ad- 

